MOS transistors are one of the most important components in modern integrated circuits. The basic structure of a MOS transistor includes a semiconductor substrate, a gate structure on the surface of the semiconductor substrate, a source region in the semiconductor substrate located on one side of the gate structure, and a drain region in the semiconductor substrate located on the other side of the gate structure. The MOS transistor operates according to the following principle: a switching signal is generated by applying a voltage on the gate structure and adjusting the electric current in the channel region under the gate structure.
With the development of semiconductor technologies, the controlling ability of the traditional planar MOS transistor on the channel current becomes weaker, causing a severe leakage current phenomenon. The fin field effect transistor (FinFET) is a new multi-gate device that typically includes a plurality of fins protruding from the surface of the semiconductor substrate, a gate structure covering a portion of the top and sidewall surfaces of the fins, a source region in the fins on one side of the gate structure, and a drain region in the fins on the other side of the gate structure.
However, the process of forming a semiconductor device, such as a planar MOS transistor or a FinFET, is quite complicated. The disclosed semiconductor device and method are directed to solve one or more problems set forth above and other problems in the art.